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In Reply to: RE: So, what's the down side, if any? nt posted by arend-jan on July 04, 2009 at 04:40:56
Completing my earlier post:
__Kentaya wrote: "There is no down side. Since the circuit is parallel with the audio signal it actually does nothing until the the maximum voltage of the tweeter element is reached and then the board engages preventing the voltage from swinging any higher. Sounds like a tube amp clipping when this occurs."
Now precisely because the board limits the maximum voltage entering the element it prevents it being more dynamic. Quad stated that the maximum voltage the panel can handle is 35 V peak. If it could handle more than that then it's dynamic range would be much broader.
This is exactly what the SUPER TREBLE PANEL I have does.
Also when the limiter kicks in Kentaya says: "Sounds like a tube amp clipping". Now what is this if not a sonic impact?
Believe me my friend the original 1950-s technology treble panel is a dead horse. Spending more money by adding to it a protection board is nothing more than flogging that dead horse.
If you are interested to see what my SUPER TREBLE PANEL looks like then
please send me an email and in my reply to it I will send you a picture
of it and provide more detail.
Best regards,
David
G'Day,
As the title says. This is not, by some weird chance, Otto Major's Jantzenisation of the original panel with a wire grid back stator and so forth is it?
Regards,
Gary Jacobson
Hi Gary,
No it is not. The panels you bought from him in 1998 when he started
manufacturing these was nothing more than a prototype, beta version
if you like. 11 years later, the present ones are now vastly different and much better.
I know because I had them both.
Best regards,
David
G'Day,
One would hope that they would have to be better and would have to judge the present crop on their performance; of course. I was mightily **unimpressed** with the originals, I can tell you. Sounded nothing whatever like an original Quad treble panel and measured poorly also with a significant loss of HF. No dust cover, and so they were a bit prone to being unreliable for that reason as well. The back stator was composed of strands of computer data cable (separated) carrying ht music signal and would flex a great deal more than a perforated plate - this is in the style of Jantzens stator (wire) designs. Nothing new there.
However, that is, as you say, 10 years ago. I would like to see a pair for review if they are available and I imagine so would kentaja. I for one, would need to have physical measurements as well as listening tests to convince me that these panels had improved at all.
So, tell us, by all means, what has changed? Materials, mode of construction? Nothing to hide. After all the original Quad materials and structure are well known, but that doesn't mean everyone has the skills to rebuild them, as you know, so I don't see a risk in publishing the basic material and structural innovations, except those you think are truly patentable, perhaps.
Oh yes, and the ones I have were not sold as "prototypes" but equivalent production replacements for the original panel. They were not.
Regards,
Gary Jacobson
Hi David,Your original statement was:
Installing protective boards will have plenty of down sides. The biggest one is that it will severely restrict the dynamic range of the speaker, ....
First I'd like to suggest a change of nomenclature, and instead of 'dynamics' use 'maximum output' which is more to the point. (Dynamics implies a range, a comparison between the low and high value. That's not what we are discussing here).
According to your statement, the speaker would have lower maximum output with the protective board than without it. But without the board, the maximum output is still limited to about the same level by the capabilities of the treble panel. So I can't agree with your original statement. Installing a protection board will not lower the maximum output (or only very slightly, and you would not want to be running your panel that hot without it).
If you change the treble panel so it can withstand higher signal voltage, then yes of course the protective board would limit the maximum SPL.
For original unrefurbished speakers, I think it's wise to install the protection boards. Why? Because old panels have lost about 4 to 6 dB of SPL (because of lowered sensitivity) and one is likely to turn up the wick far enough to burn the treble panel to a crisp. With a refurbished panel this is much less likely, in fact I have never toasted a panel even without protection.
I suppose this is because the speaker is going to distort quite a bit when playing at maximum volume, especially the stock bass panel, which (IMO) is not quite up to par with the rest of the system. The sound becomes congested and I naturally turn down the volume. That's why I don't see the point of making the treble panel arc-proof if you don't address the rest of the speaker. By the way I have plenty of ideas to do just that, but time is limiting progress in that area.
Out of curiosity I would be interested to hear more about this 'super panel', where does it come from and what does it look like? Please send me a message if you can't post it on this board.
Edits: 07/05/09 07/05/09
Well the Quad has been called a 'dead horse' many times over the decades. Some how the old horse manages to keep plodding along providing a thrilling experience for their owners!
35V is a maximum value and I believe that generally Quad stated the limit at 33V. That as a practical matter is the limit because some of the original Quad produced panels will arc before 33V is hit even when new. There was WIDE variation in build quality on the Quad plant floor in those days. I can rebuild a factory type panel that will handle 35V, even greater, without arcing, without changing a thing about the panel, just careful construction.
But even if one can develop a tweeter element that will handle a 100V and play 120dB that is not of much use. The bass elements will start bottoming out and falling all over themselves way before then. On bass heavy music they will be lucky to achieve 95dB before giving up the ghost. So the limiter in terms of SPL output of the speaker is not the tweeter element but the bass elements. A stock tweeter element working correctly will easily achieve 102dB. An improved tweeter element with greater SPL capability will not change a thing with the speakers overall SPL output so what is the point? The factory tweeter in no way limits dynamic range of the speaker.
Yes the protection board inserts some small amount of distortion into the audio signal when tripped. That is the point! You have hit the wall. Time to turn things down a bit. But when the circuit is not engaged, i.e. protecting the panel, there is no sonic impact of any kind. Better a bit of benign distortion letting you know you have hit the maximum versus a flaming panel telling you the same thing don't you think? I would say that is a more than adequate trade-off.
Most folks are thrilled with the idea they can use any amplifier they wish without any fear of damaging the speaker! Count me firmly in that group. And one of the many upsides to the board is the speaker will be more muscular and dynamic since one can use a more muscular and dynamic amp versus the flea size amps that are typically recommended.
You are correct that it is time to stop fiddling with that out-of-date 1950's technology. PJW would have said the same thing. Buy an ESL63, the better speaker anway! (Tongue firmly planted in cheek.)
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